Means for electrically heating crucibles



(No Model.)

W. MITCHELL. MEANS FOR ELEGTRIGALLY HEATING GRUCIBLES. No. 494,585. Patented Apr. 4, 1893.

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THE HOYQLATHO WASHINGTCN, D C

UNITED STATES PATENT OFFICE.

IVILLIS MITCHELL, OF MALDEN, ASSIGNOR TO THE AMERICAN ELECTRIC HEATING COMPANY, OF BOSTON, MASSACHUSETTS.

MEANS FOR ELECTRICALLY HEATING CRUCIBLES.

SPECIFICATION forming part of Letters Patent No. 494,585, dated April 4, 1893.

Application filed June 18, 1892. Serial No. 436,516- (No model.) I

To all whom it may concern.-

Be it known that I, WVILLIS MITCHELL, a citizen of the United States, residing at Malden, in the county of Middlesex and State of Massach usetts, have in vented certain new and usefulImprovements in Electrically-Heated Crucibles and Holders Therefor; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The object of this invention is to provide for heating a crucible by electricity and to especially adapt the crucible to this procedure.

The said invention consists partly in a crucible consisting of two insulated parts; and also in the combination therewith of aholder and connected circuit wires having terminals in contact with these parts respectively.

In the accompanying drawings Figure 1 represents a perspective view of a crucible and its holder embodying my invention. Fig. 2 represents the parts of the crucible and their insulating bar detached; and Fig. 3 represents a perspective view of the holder.

A and B designate the two equal longitudinal parts or sections of my crucible preferably formed by simply cutting through an ordinary plumbago crucible on the line of its axis. C designates a U-shaped bar or partition of asbestus or fire clay or a mixture of both or other insulating material, which is fitted between the edges of these parts and cemented or otherwise secured thereto completing the improved crucible. The latter may however be made in the first instance with this bar or partition embedded in itbutseparatingthe material on each side, to secure the same result.

The holder consists of two bars or rods D of electrically conducting material fastened by transverse insulated pins 01 and extending in parallel lines through a handle E beyond which they are connected to wires F G forming part of an electric circuit. The operating ends of these rods or bars are spread apart and curved at D, to receive the crucible between them, being provided with terminal V plates H H that fit the sides of it neatly.

Plate H is in contact with crucible section A and plate H wit-h crucible section B; and as these sections are insulated the electrical current must cross the intervening space, the hollowinterior of thesaid crucible,through the ore or metal therein contained, excitingahigh degree of heat in overcoming the resistance encountered, both from the plumbago of the crucible and from what it may contain.

Of course such crucibles maybe of varying sizes according to the service desired; but this invention is particularly useful in the melting or softening of small quantities of metal and the like, as for dentists and jewelers use. The form of the crucible may of course vary, the word being intended toinclude anyvessel thus constructed. Metal or other suitable material may be substituted for plumbago; but the latter is best.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. A crucible consisting of the sectionsAand B of electrically conducting material and the U-shaped insulating bar or partition C substantially as set forth.

2. In combination with a crucible consisting of two insulated parts of electrically conducting material, a holder which is provided with a handle adapted to be held by the hand and with two terminal plates in contact with the said parts respectively, these plates being insulated from each otherand forming part of an electric circuit substantially as set forth.

3. In combination with a crucible consisting of two insulated parts of conducting material a holder consisting of two bars in a handle, these bars being adapted to fit against the said parts respectively and connected to wires completing an electric circuit through them and through the said crucible substantially as set forth.

In testimony whereoflaffix my signaturein presence of two witnesses.

WILLIS MITCHELL.

Witnesses:

FRANKLIN L. PAINE, J. R. PATERSON. 

